Containers for magnetic disks protect the disks from damage during storage and shipment. One kind of conventional container comprises a cassette portion, a top cover, and a bottom cover, each formed separately by injection molding. The cassette portion is integrally formed of a rigid plastic, such as polycarbonate. It has elongate side walls that extend vertically on the upper portions and curve inwardly on the bottom portions to an open bottom, vertical end walls with U-shaped contoured tops, and an open top and open bottom. The top cover may be formed of polycarbonate, or many similar injection grade polymers. It is shaped to follow the contours of the cassette portion and to continuously align with the side walls and end walls, and typically snaps onto a catch at or rests on the lower end of the U-shaped contours in the end walls. The bottom cover may be formed of a similar polymer as the top cover and is generally rectangular and tray shaped. It engages and is frictionally retained on the open bottom of the cassette. Examples of this kind of container are found in U.S. Pat. No. 4,557,382 and U.S. Pat. No. 5,253,755.
These kinds of carriers secure disks by engaging the disks' peripheral edges. Consequently, damage to disks can occur when a container housing the disks is subject to a jolt or shock. Moreover, contact between the cassette and the disks may encourage plastic particles or other particulation to migrate to the disks. Thus, as an alternative, a second kind of container may be used to house and protect the disks, one that implements a spindle that passes through the central aperture of the disks.
A rather simple example of a disk carrier having a spindle is disclosed in Tajima, U.S. Pat. No. 4,826,005, Packaging of Information Recording Media, wherein an elongate member such as a pipe is used. Other disk carriers use fixed structured spindles incorporating spacers to separate the disks from one another, which spacers are either attachable to and detachable from the spindle or permanently attached to the spindle. Examples of these kinds of spindles are disclosed in Keohan, U.S. Pat. No. 4,253,571, Disc Container; Hennessy et al., U.S. Pat. No. 4,577,756, Protective Canister for Computer Discs; and VanSant, U.S. Pat. No. 4,754,447, Multidisk Spindle. Generally, these spacers are concentric rings intended to fit over a spindle. In addition to separating the disks, these spacers can fit snuggly against the edge of a central aperture of a disk so that the spindle can be sized to freely pass through the aperture.
To incorporate spacing means onto a spindle while allowing the spindle to freely pass through an aperture or snuggly fit against the edge of the central aperture when desired, complex mechanical means have been devised and incorporated into spindles to both expand and contract them diametrically. Examples of these spindles are Benz, U.S. Pat. No. 4,779,724, Support Structure for Annular Magnetic Recording Disks; Hansen et al., U.S. Pat. No. 6,116,416, Magnetic Hard Disk Transportation System and Method; Hyakusoku et al., U.S. Pat. No. 6,138,824, Hard Disk Carrier; and Nakamura et al., U.S. Pat. No. 6,382,413 B1, Disk Holder and Disk Storage Device. In brief, Benz et al. disclose two elongate, axially aligned cam actuating members used to effect displacement of two elongate, diametrically opposed arcuate support members away from each other. Hansen et al. discloses first a cam bar having an oval transverse profile that, when rotated along its longitudinal axis, either expands or contracts two diametrically opposed capture bridges, and second a four piece spindle having an internal lift bar that causes the outer pieces to expand outwardly when a wedge is forced under the lift bar. Hyakusoku et al. discloses spreading diametrically opposed half cylinders using a release means including a collet and coil springs. Nakamura et al. discloses using a cam actuator to spread two diametrically opposed and interconnected bars having U-shaped transverse profiles. In each of these patents, the means for expanding and contracting the spindle is a mechanical means such as a threaded or rotating device, sliding cam actuator, or insertable wedge or collet. These means are both complicated to make and are more susceptible to deterioration in a caustic environment. Moreover, abrasion by rubbing working parts is a serious source of particulation that can attach to the disks.
Therefore, it would be advantageous to have a disk carrier having a spindle that expands and contracts and is easy to make. It would also be advantageous if the spindle were simple enough to make of material that is relatively impervious to a caustic environment. It would further be advantageous if the spindle were to have a minimal number of working parts to minimize the amount of particulation created by the container.